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c906108c | 1 | /* GDB-specific functions for operating on agent expressions |
b6ba6518 | 2 | Copyright 1998, 1999, 2000, 2001 Free Software Foundation, Inc. |
c906108c | 3 | |
c5aa993b | 4 | This file is part of GDB. |
c906108c | 5 | |
c5aa993b JM |
6 | This program is free software; you can redistribute it and/or modify |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
c906108c | 10 | |
c5aa993b JM |
11 | This program is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
c906108c | 15 | |
c5aa993b JM |
16 | You should have received a copy of the GNU General Public License |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
c906108c | 20 | |
c906108c SS |
21 | #include "defs.h" |
22 | #include "symtab.h" | |
23 | #include "symfile.h" | |
24 | #include "gdbtypes.h" | |
25 | #include "value.h" | |
26 | #include "expression.h" | |
27 | #include "command.h" | |
28 | #include "gdbcmd.h" | |
29 | #include "frame.h" | |
30 | #include "target.h" | |
31 | #include "ax.h" | |
32 | #include "ax-gdb.h" | |
309367d4 | 33 | #include "gdb_string.h" |
c906108c | 34 | |
6426a772 JM |
35 | /* To make sense of this file, you should read doc/agentexpr.texi. |
36 | Then look at the types and enums in ax-gdb.h. For the code itself, | |
37 | look at gen_expr, towards the bottom; that's the main function that | |
38 | looks at the GDB expressions and calls everything else to generate | |
39 | code. | |
c906108c SS |
40 | |
41 | I'm beginning to wonder whether it wouldn't be nicer to internally | |
42 | generate trees, with types, and then spit out the bytecode in | |
43 | linear form afterwards; we could generate fewer `swap', `ext', and | |
44 | `zero_ext' bytecodes that way; it would make good constant folding | |
45 | easier, too. But at the moment, I think we should be willing to | |
46 | pay for the simplicity of this code with less-than-optimal bytecode | |
47 | strings. | |
48 | ||
c5aa993b JM |
49 | Remember, "GBD" stands for "Great Britain, Dammit!" So be careful. */ |
50 | \f | |
c906108c SS |
51 | |
52 | ||
c906108c SS |
53 | /* Prototypes for local functions. */ |
54 | ||
55 | /* There's a standard order to the arguments of these functions: | |
56 | union exp_element ** --- pointer into expression | |
57 | struct agent_expr * --- agent expression buffer to generate code into | |
58 | struct axs_value * --- describes value left on top of stack */ | |
c5aa993b | 59 | |
a14ed312 KB |
60 | static struct value *const_var_ref (struct symbol *var); |
61 | static struct value *const_expr (union exp_element **pc); | |
62 | static struct value *maybe_const_expr (union exp_element **pc); | |
63 | ||
64 | static void gen_traced_pop (struct agent_expr *, struct axs_value *); | |
65 | ||
66 | static void gen_sign_extend (struct agent_expr *, struct type *); | |
67 | static void gen_extend (struct agent_expr *, struct type *); | |
68 | static void gen_fetch (struct agent_expr *, struct type *); | |
69 | static void gen_left_shift (struct agent_expr *, int); | |
70 | ||
71 | ||
72 | static void gen_frame_args_address (struct agent_expr *); | |
73 | static void gen_frame_locals_address (struct agent_expr *); | |
74 | static void gen_offset (struct agent_expr *ax, int offset); | |
75 | static void gen_sym_offset (struct agent_expr *, struct symbol *); | |
76 | static void gen_var_ref (struct agent_expr *ax, | |
77 | struct axs_value *value, struct symbol *var); | |
78 | ||
79 | ||
80 | static void gen_int_literal (struct agent_expr *ax, | |
81 | struct axs_value *value, | |
82 | LONGEST k, struct type *type); | |
83 | ||
84 | ||
85 | static void require_rvalue (struct agent_expr *ax, struct axs_value *value); | |
86 | static void gen_usual_unary (struct agent_expr *ax, struct axs_value *value); | |
87 | static int type_wider_than (struct type *type1, struct type *type2); | |
88 | static struct type *max_type (struct type *type1, struct type *type2); | |
89 | static void gen_conversion (struct agent_expr *ax, | |
90 | struct type *from, struct type *to); | |
91 | static int is_nontrivial_conversion (struct type *from, struct type *to); | |
92 | static void gen_usual_arithmetic (struct agent_expr *ax, | |
93 | struct axs_value *value1, | |
94 | struct axs_value *value2); | |
95 | static void gen_integral_promotions (struct agent_expr *ax, | |
96 | struct axs_value *value); | |
97 | static void gen_cast (struct agent_expr *ax, | |
98 | struct axs_value *value, struct type *type); | |
99 | static void gen_scale (struct agent_expr *ax, | |
100 | enum agent_op op, struct type *type); | |
101 | static void gen_add (struct agent_expr *ax, | |
102 | struct axs_value *value, | |
103 | struct axs_value *value1, | |
104 | struct axs_value *value2, char *name); | |
105 | static void gen_sub (struct agent_expr *ax, | |
106 | struct axs_value *value, | |
107 | struct axs_value *value1, struct axs_value *value2); | |
108 | static void gen_binop (struct agent_expr *ax, | |
109 | struct axs_value *value, | |
110 | struct axs_value *value1, | |
111 | struct axs_value *value2, | |
112 | enum agent_op op, | |
113 | enum agent_op op_unsigned, int may_carry, char *name); | |
114 | static void gen_logical_not (struct agent_expr *ax, struct axs_value *value); | |
115 | static void gen_complement (struct agent_expr *ax, struct axs_value *value); | |
116 | static void gen_deref (struct agent_expr *, struct axs_value *); | |
117 | static void gen_address_of (struct agent_expr *, struct axs_value *); | |
118 | static int find_field (struct type *type, char *name); | |
119 | static void gen_bitfield_ref (struct agent_expr *ax, | |
120 | struct axs_value *value, | |
121 | struct type *type, int start, int end); | |
122 | static void gen_struct_ref (struct agent_expr *ax, | |
123 | struct axs_value *value, | |
124 | char *field, | |
125 | char *operator_name, char *operand_name); | |
126 | static void gen_repeat (union exp_element **pc, | |
127 | struct agent_expr *ax, struct axs_value *value); | |
128 | static void gen_sizeof (union exp_element **pc, | |
129 | struct agent_expr *ax, struct axs_value *value); | |
130 | static void gen_expr (union exp_element **pc, | |
131 | struct agent_expr *ax, struct axs_value *value); | |
c5aa993b | 132 | |
d9fcf2fb | 133 | static void print_axs_value (struct ui_file *f, struct axs_value * value); |
a14ed312 | 134 | static void agent_command (char *exp, int from_tty); |
c906108c | 135 | \f |
c5aa993b | 136 | |
c906108c SS |
137 | /* Detecting constant expressions. */ |
138 | ||
139 | /* If the variable reference at *PC is a constant, return its value. | |
140 | Otherwise, return zero. | |
141 | ||
142 | Hey, Wally! How can a variable reference be a constant? | |
143 | ||
144 | Well, Beav, this function really handles the OP_VAR_VALUE operator, | |
145 | not specifically variable references. GDB uses OP_VAR_VALUE to | |
146 | refer to any kind of symbolic reference: function names, enum | |
147 | elements, and goto labels are all handled through the OP_VAR_VALUE | |
148 | operator, even though they're constants. It makes sense given the | |
149 | situation. | |
150 | ||
151 | Gee, Wally, don'cha wonder sometimes if data representations that | |
152 | subvert commonly accepted definitions of terms in favor of heavily | |
153 | context-specific interpretations are really just a tool of the | |
154 | programming hegemony to preserve their power and exclude the | |
155 | proletariat? */ | |
156 | ||
157 | static struct value * | |
fba45db2 | 158 | const_var_ref (struct symbol *var) |
c906108c SS |
159 | { |
160 | struct type *type = SYMBOL_TYPE (var); | |
161 | ||
162 | switch (SYMBOL_CLASS (var)) | |
163 | { | |
164 | case LOC_CONST: | |
165 | return value_from_longest (type, (LONGEST) SYMBOL_VALUE (var)); | |
166 | ||
167 | case LOC_LABEL: | |
4478b372 | 168 | return value_from_pointer (type, (CORE_ADDR) SYMBOL_VALUE_ADDRESS (var)); |
c906108c SS |
169 | |
170 | default: | |
171 | return 0; | |
172 | } | |
173 | } | |
174 | ||
175 | ||
176 | /* If the expression starting at *PC has a constant value, return it. | |
177 | Otherwise, return zero. If we return a value, then *PC will be | |
178 | advanced to the end of it. If we return zero, *PC could be | |
179 | anywhere. */ | |
180 | static struct value * | |
fba45db2 | 181 | const_expr (union exp_element **pc) |
c906108c SS |
182 | { |
183 | enum exp_opcode op = (*pc)->opcode; | |
184 | struct value *v1; | |
185 | ||
186 | switch (op) | |
187 | { | |
188 | case OP_LONG: | |
189 | { | |
190 | struct type *type = (*pc)[1].type; | |
191 | LONGEST k = (*pc)[2].longconst; | |
192 | (*pc) += 4; | |
193 | return value_from_longest (type, k); | |
194 | } | |
195 | ||
196 | case OP_VAR_VALUE: | |
197 | { | |
198 | struct value *v = const_var_ref ((*pc)[2].symbol); | |
199 | (*pc) += 4; | |
200 | return v; | |
201 | } | |
202 | ||
c5aa993b | 203 | /* We could add more operators in here. */ |
c906108c SS |
204 | |
205 | case UNOP_NEG: | |
206 | (*pc)++; | |
207 | v1 = const_expr (pc); | |
208 | if (v1) | |
209 | return value_neg (v1); | |
210 | else | |
211 | return 0; | |
212 | ||
213 | default: | |
214 | return 0; | |
215 | } | |
216 | } | |
217 | ||
218 | ||
219 | /* Like const_expr, but guarantee also that *PC is undisturbed if the | |
220 | expression is not constant. */ | |
221 | static struct value * | |
fba45db2 | 222 | maybe_const_expr (union exp_element **pc) |
c906108c SS |
223 | { |
224 | union exp_element *tentative_pc = *pc; | |
225 | struct value *v = const_expr (&tentative_pc); | |
226 | ||
227 | /* If we got a value, then update the real PC. */ | |
228 | if (v) | |
229 | *pc = tentative_pc; | |
c5aa993b | 230 | |
c906108c SS |
231 | return v; |
232 | } | |
c906108c | 233 | \f |
c5aa993b | 234 | |
c906108c SS |
235 | /* Generating bytecode from GDB expressions: general assumptions */ |
236 | ||
237 | /* Here are a few general assumptions made throughout the code; if you | |
238 | want to make a change that contradicts one of these, then you'd | |
239 | better scan things pretty thoroughly. | |
240 | ||
241 | - We assume that all values occupy one stack element. For example, | |
c5aa993b JM |
242 | sometimes we'll swap to get at the left argument to a binary |
243 | operator. If we decide that void values should occupy no stack | |
244 | elements, or that synthetic arrays (whose size is determined at | |
245 | run time, created by the `@' operator) should occupy two stack | |
246 | elements (address and length), then this will cause trouble. | |
c906108c SS |
247 | |
248 | - We assume the stack elements are infinitely wide, and that we | |
c5aa993b JM |
249 | don't have to worry what happens if the user requests an |
250 | operation that is wider than the actual interpreter's stack. | |
251 | That is, it's up to the interpreter to handle directly all the | |
252 | integer widths the user has access to. (Woe betide the language | |
253 | with bignums!) | |
c906108c SS |
254 | |
255 | - We don't support side effects. Thus, we don't have to worry about | |
c5aa993b | 256 | GCC's generalized lvalues, function calls, etc. |
c906108c SS |
257 | |
258 | - We don't support floating point. Many places where we switch on | |
c5aa993b JM |
259 | some type don't bother to include cases for floating point; there |
260 | may be even more subtle ways this assumption exists. For | |
261 | example, the arguments to % must be integers. | |
c906108c SS |
262 | |
263 | - We assume all subexpressions have a static, unchanging type. If | |
c5aa993b JM |
264 | we tried to support convenience variables, this would be a |
265 | problem. | |
c906108c SS |
266 | |
267 | - All values on the stack should always be fully zero- or | |
c5aa993b JM |
268 | sign-extended. |
269 | ||
270 | (I wasn't sure whether to choose this or its opposite --- that | |
271 | only addresses are assumed extended --- but it turns out that | |
272 | neither convention completely eliminates spurious extend | |
273 | operations (if everything is always extended, then you have to | |
274 | extend after add, because it could overflow; if nothing is | |
275 | extended, then you end up producing extends whenever you change | |
276 | sizes), and this is simpler.) */ | |
c906108c | 277 | \f |
c5aa993b | 278 | |
c906108c SS |
279 | /* Generating bytecode from GDB expressions: the `trace' kludge */ |
280 | ||
281 | /* The compiler in this file is a general-purpose mechanism for | |
282 | translating GDB expressions into bytecode. One ought to be able to | |
283 | find a million and one uses for it. | |
284 | ||
285 | However, at the moment it is HOPELESSLY BRAIN-DAMAGED for the sake | |
286 | of expediency. Let he who is without sin cast the first stone. | |
287 | ||
288 | For the data tracing facility, we need to insert `trace' bytecodes | |
289 | before each data fetch; this records all the memory that the | |
290 | expression touches in the course of evaluation, so that memory will | |
291 | be available when the user later tries to evaluate the expression | |
292 | in GDB. | |
293 | ||
294 | This should be done (I think) in a post-processing pass, that walks | |
295 | an arbitrary agent expression and inserts `trace' operations at the | |
296 | appropriate points. But it's much faster to just hack them | |
297 | directly into the code. And since we're in a crunch, that's what | |
298 | I've done. | |
299 | ||
300 | Setting the flag trace_kludge to non-zero enables the code that | |
301 | emits the trace bytecodes at the appropriate points. */ | |
302 | static int trace_kludge; | |
303 | ||
304 | /* Trace the lvalue on the stack, if it needs it. In either case, pop | |
305 | the value. Useful on the left side of a comma, and at the end of | |
306 | an expression being used for tracing. */ | |
307 | static void | |
fba45db2 | 308 | gen_traced_pop (struct agent_expr *ax, struct axs_value *value) |
c906108c SS |
309 | { |
310 | if (trace_kludge) | |
311 | switch (value->kind) | |
312 | { | |
313 | case axs_rvalue: | |
314 | /* We don't trace rvalues, just the lvalues necessary to | |
c5aa993b | 315 | produce them. So just dispose of this value. */ |
c906108c SS |
316 | ax_simple (ax, aop_pop); |
317 | break; | |
318 | ||
319 | case axs_lvalue_memory: | |
320 | { | |
321 | int length = TYPE_LENGTH (value->type); | |
322 | ||
323 | /* There's no point in trying to use a trace_quick bytecode | |
324 | here, since "trace_quick SIZE pop" is three bytes, whereas | |
325 | "const8 SIZE trace" is also three bytes, does the same | |
326 | thing, and the simplest code which generates that will also | |
327 | work correctly for objects with large sizes. */ | |
328 | ax_const_l (ax, length); | |
329 | ax_simple (ax, aop_trace); | |
330 | } | |
c5aa993b | 331 | break; |
c906108c SS |
332 | |
333 | case axs_lvalue_register: | |
334 | /* We need to mention the register somewhere in the bytecode, | |
335 | so ax_reqs will pick it up and add it to the mask of | |
336 | registers used. */ | |
337 | ax_reg (ax, value->u.reg); | |
338 | ax_simple (ax, aop_pop); | |
339 | break; | |
340 | } | |
341 | else | |
342 | /* If we're not tracing, just pop the value. */ | |
343 | ax_simple (ax, aop_pop); | |
344 | } | |
c5aa993b | 345 | \f |
c906108c SS |
346 | |
347 | ||
c906108c SS |
348 | /* Generating bytecode from GDB expressions: helper functions */ |
349 | ||
350 | /* Assume that the lower bits of the top of the stack is a value of | |
351 | type TYPE, and the upper bits are zero. Sign-extend if necessary. */ | |
352 | static void | |
fba45db2 | 353 | gen_sign_extend (struct agent_expr *ax, struct type *type) |
c906108c SS |
354 | { |
355 | /* Do we need to sign-extend this? */ | |
c5aa993b | 356 | if (!TYPE_UNSIGNED (type)) |
0004e5a2 | 357 | ax_ext (ax, TYPE_LENGTH (type) * TARGET_CHAR_BIT); |
c906108c SS |
358 | } |
359 | ||
360 | ||
361 | /* Assume the lower bits of the top of the stack hold a value of type | |
362 | TYPE, and the upper bits are garbage. Sign-extend or truncate as | |
363 | needed. */ | |
364 | static void | |
fba45db2 | 365 | gen_extend (struct agent_expr *ax, struct type *type) |
c906108c | 366 | { |
0004e5a2 | 367 | int bits = TYPE_LENGTH (type) * TARGET_CHAR_BIT; |
c906108c SS |
368 | /* I just had to. */ |
369 | ((TYPE_UNSIGNED (type) ? ax_zero_ext : ax_ext) (ax, bits)); | |
370 | } | |
371 | ||
372 | ||
373 | /* Assume that the top of the stack contains a value of type "pointer | |
374 | to TYPE"; generate code to fetch its value. Note that TYPE is the | |
375 | target type, not the pointer type. */ | |
376 | static void | |
fba45db2 | 377 | gen_fetch (struct agent_expr *ax, struct type *type) |
c906108c SS |
378 | { |
379 | if (trace_kludge) | |
380 | { | |
381 | /* Record the area of memory we're about to fetch. */ | |
382 | ax_trace_quick (ax, TYPE_LENGTH (type)); | |
383 | } | |
384 | ||
0004e5a2 | 385 | switch (TYPE_CODE (type)) |
c906108c SS |
386 | { |
387 | case TYPE_CODE_PTR: | |
388 | case TYPE_CODE_ENUM: | |
389 | case TYPE_CODE_INT: | |
390 | case TYPE_CODE_CHAR: | |
391 | /* It's a scalar value, so we know how to dereference it. How | |
392 | many bytes long is it? */ | |
0004e5a2 | 393 | switch (TYPE_LENGTH (type)) |
c906108c | 394 | { |
c5aa993b JM |
395 | case 8 / TARGET_CHAR_BIT: |
396 | ax_simple (ax, aop_ref8); | |
397 | break; | |
398 | case 16 / TARGET_CHAR_BIT: | |
399 | ax_simple (ax, aop_ref16); | |
400 | break; | |
401 | case 32 / TARGET_CHAR_BIT: | |
402 | ax_simple (ax, aop_ref32); | |
403 | break; | |
404 | case 64 / TARGET_CHAR_BIT: | |
405 | ax_simple (ax, aop_ref64); | |
406 | break; | |
c906108c SS |
407 | |
408 | /* Either our caller shouldn't have asked us to dereference | |
409 | that pointer (other code's fault), or we're not | |
410 | implementing something we should be (this code's fault). | |
411 | In any case, it's a bug the user shouldn't see. */ | |
412 | default: | |
8e65ff28 AC |
413 | internal_error (__FILE__, __LINE__, |
414 | "gen_fetch: strange size"); | |
c906108c SS |
415 | } |
416 | ||
417 | gen_sign_extend (ax, type); | |
418 | break; | |
419 | ||
420 | default: | |
421 | /* Either our caller shouldn't have asked us to dereference that | |
c5aa993b JM |
422 | pointer (other code's fault), or we're not implementing |
423 | something we should be (this code's fault). In any case, | |
424 | it's a bug the user shouldn't see. */ | |
8e65ff28 AC |
425 | internal_error (__FILE__, __LINE__, |
426 | "gen_fetch: bad type code"); | |
c906108c SS |
427 | } |
428 | } | |
429 | ||
430 | ||
431 | /* Generate code to left shift the top of the stack by DISTANCE bits, or | |
432 | right shift it by -DISTANCE bits if DISTANCE < 0. This generates | |
433 | unsigned (logical) right shifts. */ | |
434 | static void | |
fba45db2 | 435 | gen_left_shift (struct agent_expr *ax, int distance) |
c906108c SS |
436 | { |
437 | if (distance > 0) | |
438 | { | |
439 | ax_const_l (ax, distance); | |
440 | ax_simple (ax, aop_lsh); | |
441 | } | |
442 | else if (distance < 0) | |
443 | { | |
444 | ax_const_l (ax, -distance); | |
445 | ax_simple (ax, aop_rsh_unsigned); | |
446 | } | |
447 | } | |
c5aa993b | 448 | \f |
c906108c SS |
449 | |
450 | ||
c906108c SS |
451 | /* Generating bytecode from GDB expressions: symbol references */ |
452 | ||
453 | /* Generate code to push the base address of the argument portion of | |
454 | the top stack frame. */ | |
455 | static void | |
fba45db2 | 456 | gen_frame_args_address (struct agent_expr *ax) |
c906108c | 457 | { |
39d4ef09 AC |
458 | int frame_reg; |
459 | LONGEST frame_offset; | |
c906108c SS |
460 | |
461 | TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset); | |
c5aa993b | 462 | ax_reg (ax, frame_reg); |
c906108c SS |
463 | gen_offset (ax, frame_offset); |
464 | } | |
465 | ||
466 | ||
467 | /* Generate code to push the base address of the locals portion of the | |
468 | top stack frame. */ | |
469 | static void | |
fba45db2 | 470 | gen_frame_locals_address (struct agent_expr *ax) |
c906108c | 471 | { |
39d4ef09 AC |
472 | int frame_reg; |
473 | LONGEST frame_offset; | |
c906108c SS |
474 | |
475 | TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset); | |
c5aa993b | 476 | ax_reg (ax, frame_reg); |
c906108c SS |
477 | gen_offset (ax, frame_offset); |
478 | } | |
479 | ||
480 | ||
481 | /* Generate code to add OFFSET to the top of the stack. Try to | |
482 | generate short and readable code. We use this for getting to | |
483 | variables on the stack, and structure members. If we were | |
484 | programming in ML, it would be clearer why these are the same | |
485 | thing. */ | |
486 | static void | |
fba45db2 | 487 | gen_offset (struct agent_expr *ax, int offset) |
c906108c SS |
488 | { |
489 | /* It would suffice to simply push the offset and add it, but this | |
490 | makes it easier to read positive and negative offsets in the | |
491 | bytecode. */ | |
492 | if (offset > 0) | |
493 | { | |
494 | ax_const_l (ax, offset); | |
495 | ax_simple (ax, aop_add); | |
496 | } | |
497 | else if (offset < 0) | |
498 | { | |
499 | ax_const_l (ax, -offset); | |
500 | ax_simple (ax, aop_sub); | |
501 | } | |
502 | } | |
503 | ||
504 | ||
505 | /* In many cases, a symbol's value is the offset from some other | |
506 | address (stack frame, base register, etc.) Generate code to add | |
507 | VAR's value to the top of the stack. */ | |
508 | static void | |
fba45db2 | 509 | gen_sym_offset (struct agent_expr *ax, struct symbol *var) |
c906108c SS |
510 | { |
511 | gen_offset (ax, SYMBOL_VALUE (var)); | |
512 | } | |
513 | ||
514 | ||
515 | /* Generate code for a variable reference to AX. The variable is the | |
516 | symbol VAR. Set VALUE to describe the result. */ | |
517 | ||
518 | static void | |
fba45db2 | 519 | gen_var_ref (struct agent_expr *ax, struct axs_value *value, struct symbol *var) |
c906108c SS |
520 | { |
521 | /* Dereference any typedefs. */ | |
522 | value->type = check_typedef (SYMBOL_TYPE (var)); | |
523 | ||
524 | /* I'm imitating the code in read_var_value. */ | |
525 | switch (SYMBOL_CLASS (var)) | |
526 | { | |
527 | case LOC_CONST: /* A constant, like an enum value. */ | |
528 | ax_const_l (ax, (LONGEST) SYMBOL_VALUE (var)); | |
529 | value->kind = axs_rvalue; | |
530 | break; | |
531 | ||
532 | case LOC_LABEL: /* A goto label, being used as a value. */ | |
533 | ax_const_l (ax, (LONGEST) SYMBOL_VALUE_ADDRESS (var)); | |
534 | value->kind = axs_rvalue; | |
535 | break; | |
536 | ||
537 | case LOC_CONST_BYTES: | |
8e65ff28 AC |
538 | internal_error (__FILE__, __LINE__, |
539 | "gen_var_ref: LOC_CONST_BYTES symbols are not supported"); | |
c906108c SS |
540 | |
541 | /* Variable at a fixed location in memory. Easy. */ | |
542 | case LOC_STATIC: | |
543 | /* Push the address of the variable. */ | |
544 | ax_const_l (ax, SYMBOL_VALUE_ADDRESS (var)); | |
545 | value->kind = axs_lvalue_memory; | |
546 | break; | |
547 | ||
548 | case LOC_ARG: /* var lives in argument area of frame */ | |
549 | gen_frame_args_address (ax); | |
550 | gen_sym_offset (ax, var); | |
551 | value->kind = axs_lvalue_memory; | |
552 | break; | |
553 | ||
554 | case LOC_REF_ARG: /* As above, but the frame slot really | |
555 | holds the address of the variable. */ | |
556 | gen_frame_args_address (ax); | |
557 | gen_sym_offset (ax, var); | |
558 | /* Don't assume any particular pointer size. */ | |
559 | gen_fetch (ax, lookup_pointer_type (builtin_type_void)); | |
560 | value->kind = axs_lvalue_memory; | |
561 | break; | |
562 | ||
563 | case LOC_LOCAL: /* var lives in locals area of frame */ | |
564 | case LOC_LOCAL_ARG: | |
565 | gen_frame_locals_address (ax); | |
566 | gen_sym_offset (ax, var); | |
567 | value->kind = axs_lvalue_memory; | |
568 | break; | |
569 | ||
570 | case LOC_BASEREG: /* relative to some base register */ | |
571 | case LOC_BASEREG_ARG: | |
572 | ax_reg (ax, SYMBOL_BASEREG (var)); | |
573 | gen_sym_offset (ax, var); | |
574 | value->kind = axs_lvalue_memory; | |
575 | break; | |
576 | ||
577 | case LOC_TYPEDEF: | |
578 | error ("Cannot compute value of typedef `%s'.", | |
579 | SYMBOL_SOURCE_NAME (var)); | |
580 | break; | |
581 | ||
582 | case LOC_BLOCK: | |
583 | ax_const_l (ax, BLOCK_START (SYMBOL_BLOCK_VALUE (var))); | |
584 | value->kind = axs_rvalue; | |
585 | break; | |
586 | ||
587 | case LOC_REGISTER: | |
588 | case LOC_REGPARM: | |
589 | /* Don't generate any code at all; in the process of treating | |
590 | this as an lvalue or rvalue, the caller will generate the | |
591 | right code. */ | |
592 | value->kind = axs_lvalue_register; | |
593 | value->u.reg = SYMBOL_VALUE (var); | |
594 | break; | |
595 | ||
596 | /* A lot like LOC_REF_ARG, but the pointer lives directly in a | |
c5aa993b JM |
597 | register, not on the stack. Simpler than LOC_REGISTER and |
598 | LOC_REGPARM, because it's just like any other case where the | |
599 | thing has a real address. */ | |
c906108c SS |
600 | case LOC_REGPARM_ADDR: |
601 | ax_reg (ax, SYMBOL_VALUE (var)); | |
602 | value->kind = axs_lvalue_memory; | |
603 | break; | |
604 | ||
605 | case LOC_UNRESOLVED: | |
606 | { | |
c5aa993b JM |
607 | struct minimal_symbol *msym |
608 | = lookup_minimal_symbol (SYMBOL_NAME (var), NULL, NULL); | |
609 | if (!msym) | |
c906108c | 610 | error ("Couldn't resolve symbol `%s'.", SYMBOL_SOURCE_NAME (var)); |
c5aa993b | 611 | |
c906108c SS |
612 | /* Push the address of the variable. */ |
613 | ax_const_l (ax, SYMBOL_VALUE_ADDRESS (msym)); | |
614 | value->kind = axs_lvalue_memory; | |
615 | } | |
c5aa993b | 616 | break; |
c906108c SS |
617 | |
618 | case LOC_OPTIMIZED_OUT: | |
619 | error ("The variable `%s' has been optimized out.", | |
620 | SYMBOL_SOURCE_NAME (var)); | |
621 | break; | |
622 | ||
623 | default: | |
624 | error ("Cannot find value of botched symbol `%s'.", | |
625 | SYMBOL_SOURCE_NAME (var)); | |
626 | break; | |
627 | } | |
628 | } | |
c5aa993b | 629 | \f |
c906108c SS |
630 | |
631 | ||
c906108c SS |
632 | /* Generating bytecode from GDB expressions: literals */ |
633 | ||
634 | static void | |
fba45db2 KB |
635 | gen_int_literal (struct agent_expr *ax, struct axs_value *value, LONGEST k, |
636 | struct type *type) | |
c906108c SS |
637 | { |
638 | ax_const_l (ax, k); | |
639 | value->kind = axs_rvalue; | |
640 | value->type = type; | |
641 | } | |
c5aa993b | 642 | \f |
c906108c SS |
643 | |
644 | ||
c906108c SS |
645 | /* Generating bytecode from GDB expressions: unary conversions, casts */ |
646 | ||
647 | /* Take what's on the top of the stack (as described by VALUE), and | |
648 | try to make an rvalue out of it. Signal an error if we can't do | |
649 | that. */ | |
650 | static void | |
fba45db2 | 651 | require_rvalue (struct agent_expr *ax, struct axs_value *value) |
c906108c SS |
652 | { |
653 | switch (value->kind) | |
654 | { | |
655 | case axs_rvalue: | |
656 | /* It's already an rvalue. */ | |
657 | break; | |
658 | ||
659 | case axs_lvalue_memory: | |
660 | /* The top of stack is the address of the object. Dereference. */ | |
661 | gen_fetch (ax, value->type); | |
662 | break; | |
663 | ||
664 | case axs_lvalue_register: | |
665 | /* There's nothing on the stack, but value->u.reg is the | |
666 | register number containing the value. | |
667 | ||
c5aa993b JM |
668 | When we add floating-point support, this is going to have to |
669 | change. What about SPARC register pairs, for example? */ | |
c906108c SS |
670 | ax_reg (ax, value->u.reg); |
671 | gen_extend (ax, value->type); | |
672 | break; | |
673 | } | |
674 | ||
675 | value->kind = axs_rvalue; | |
676 | } | |
677 | ||
678 | ||
679 | /* Assume the top of the stack is described by VALUE, and perform the | |
680 | usual unary conversions. This is motivated by ANSI 6.2.2, but of | |
681 | course GDB expressions are not ANSI; they're the mishmash union of | |
682 | a bunch of languages. Rah. | |
683 | ||
684 | NOTE! This function promises to produce an rvalue only when the | |
685 | incoming value is of an appropriate type. In other words, the | |
686 | consumer of the value this function produces may assume the value | |
687 | is an rvalue only after checking its type. | |
688 | ||
689 | The immediate issue is that if the user tries to use a structure or | |
690 | union as an operand of, say, the `+' operator, we don't want to try | |
691 | to convert that structure to an rvalue; require_rvalue will bomb on | |
692 | structs and unions. Rather, we want to simply pass the struct | |
693 | lvalue through unchanged, and let `+' raise an error. */ | |
694 | ||
695 | static void | |
fba45db2 | 696 | gen_usual_unary (struct agent_expr *ax, struct axs_value *value) |
c906108c SS |
697 | { |
698 | /* We don't have to generate any code for the usual integral | |
699 | conversions, since values are always represented as full-width on | |
700 | the stack. Should we tweak the type? */ | |
701 | ||
702 | /* Some types require special handling. */ | |
0004e5a2 | 703 | switch (TYPE_CODE (value->type)) |
c906108c SS |
704 | { |
705 | /* Functions get converted to a pointer to the function. */ | |
706 | case TYPE_CODE_FUNC: | |
707 | value->type = lookup_pointer_type (value->type); | |
708 | value->kind = axs_rvalue; /* Should always be true, but just in case. */ | |
709 | break; | |
710 | ||
711 | /* Arrays get converted to a pointer to their first element, and | |
c5aa993b | 712 | are no longer an lvalue. */ |
c906108c SS |
713 | case TYPE_CODE_ARRAY: |
714 | { | |
715 | struct type *elements = TYPE_TARGET_TYPE (value->type); | |
716 | value->type = lookup_pointer_type (elements); | |
717 | value->kind = axs_rvalue; | |
718 | /* We don't need to generate any code; the address of the array | |
719 | is also the address of its first element. */ | |
720 | } | |
c5aa993b | 721 | break; |
c906108c | 722 | |
c5aa993b JM |
723 | /* Don't try to convert structures and unions to rvalues. Let the |
724 | consumer signal an error. */ | |
c906108c SS |
725 | case TYPE_CODE_STRUCT: |
726 | case TYPE_CODE_UNION: | |
727 | return; | |
728 | ||
729 | /* If the value is an enum, call it an integer. */ | |
730 | case TYPE_CODE_ENUM: | |
731 | value->type = builtin_type_int; | |
732 | break; | |
733 | } | |
734 | ||
735 | /* If the value is an lvalue, dereference it. */ | |
736 | require_rvalue (ax, value); | |
737 | } | |
738 | ||
739 | ||
740 | /* Return non-zero iff the type TYPE1 is considered "wider" than the | |
741 | type TYPE2, according to the rules described in gen_usual_arithmetic. */ | |
742 | static int | |
fba45db2 | 743 | type_wider_than (struct type *type1, struct type *type2) |
c906108c SS |
744 | { |
745 | return (TYPE_LENGTH (type1) > TYPE_LENGTH (type2) | |
746 | || (TYPE_LENGTH (type1) == TYPE_LENGTH (type2) | |
747 | && TYPE_UNSIGNED (type1) | |
c5aa993b | 748 | && !TYPE_UNSIGNED (type2))); |
c906108c SS |
749 | } |
750 | ||
751 | ||
752 | /* Return the "wider" of the two types TYPE1 and TYPE2. */ | |
753 | static struct type * | |
fba45db2 | 754 | max_type (struct type *type1, struct type *type2) |
c906108c SS |
755 | { |
756 | return type_wider_than (type1, type2) ? type1 : type2; | |
757 | } | |
758 | ||
759 | ||
760 | /* Generate code to convert a scalar value of type FROM to type TO. */ | |
761 | static void | |
fba45db2 | 762 | gen_conversion (struct agent_expr *ax, struct type *from, struct type *to) |
c906108c SS |
763 | { |
764 | /* Perhaps there is a more graceful way to state these rules. */ | |
765 | ||
766 | /* If we're converting to a narrower type, then we need to clear out | |
767 | the upper bits. */ | |
768 | if (TYPE_LENGTH (to) < TYPE_LENGTH (from)) | |
769 | gen_extend (ax, from); | |
770 | ||
771 | /* If the two values have equal width, but different signednesses, | |
772 | then we need to extend. */ | |
773 | else if (TYPE_LENGTH (to) == TYPE_LENGTH (from)) | |
774 | { | |
775 | if (TYPE_UNSIGNED (from) != TYPE_UNSIGNED (to)) | |
776 | gen_extend (ax, to); | |
777 | } | |
778 | ||
779 | /* If we're converting to a wider type, and becoming unsigned, then | |
780 | we need to zero out any possible sign bits. */ | |
781 | else if (TYPE_LENGTH (to) > TYPE_LENGTH (from)) | |
782 | { | |
783 | if (TYPE_UNSIGNED (to)) | |
784 | gen_extend (ax, to); | |
785 | } | |
786 | } | |
787 | ||
788 | ||
789 | /* Return non-zero iff the type FROM will require any bytecodes to be | |
790 | emitted to be converted to the type TO. */ | |
791 | static int | |
fba45db2 | 792 | is_nontrivial_conversion (struct type *from, struct type *to) |
c906108c SS |
793 | { |
794 | struct agent_expr *ax = new_agent_expr (0); | |
795 | int nontrivial; | |
796 | ||
797 | /* Actually generate the code, and see if anything came out. At the | |
798 | moment, it would be trivial to replicate the code in | |
799 | gen_conversion here, but in the future, when we're supporting | |
800 | floating point and the like, it may not be. Doing things this | |
801 | way allows this function to be independent of the logic in | |
802 | gen_conversion. */ | |
803 | gen_conversion (ax, from, to); | |
804 | nontrivial = ax->len > 0; | |
805 | free_agent_expr (ax); | |
806 | return nontrivial; | |
807 | } | |
808 | ||
809 | ||
810 | /* Generate code to perform the "usual arithmetic conversions" (ANSI C | |
811 | 6.2.1.5) for the two operands of an arithmetic operator. This | |
812 | effectively finds a "least upper bound" type for the two arguments, | |
813 | and promotes each argument to that type. *VALUE1 and *VALUE2 | |
814 | describe the values as they are passed in, and as they are left. */ | |
815 | static void | |
fba45db2 KB |
816 | gen_usual_arithmetic (struct agent_expr *ax, struct axs_value *value1, |
817 | struct axs_value *value2) | |
c906108c SS |
818 | { |
819 | /* Do the usual binary conversions. */ | |
820 | if (TYPE_CODE (value1->type) == TYPE_CODE_INT | |
821 | && TYPE_CODE (value2->type) == TYPE_CODE_INT) | |
822 | { | |
823 | /* The ANSI integral promotions seem to work this way: Order the | |
c5aa993b JM |
824 | integer types by size, and then by signedness: an n-bit |
825 | unsigned type is considered "wider" than an n-bit signed | |
826 | type. Promote to the "wider" of the two types, and always | |
827 | promote at least to int. */ | |
c906108c SS |
828 | struct type *target = max_type (builtin_type_int, |
829 | max_type (value1->type, value2->type)); | |
830 | ||
831 | /* Deal with value2, on the top of the stack. */ | |
832 | gen_conversion (ax, value2->type, target); | |
833 | ||
834 | /* Deal with value1, not on the top of the stack. Don't | |
835 | generate the `swap' instructions if we're not actually going | |
836 | to do anything. */ | |
837 | if (is_nontrivial_conversion (value1->type, target)) | |
838 | { | |
839 | ax_simple (ax, aop_swap); | |
840 | gen_conversion (ax, value1->type, target); | |
841 | ax_simple (ax, aop_swap); | |
842 | } | |
843 | ||
844 | value1->type = value2->type = target; | |
845 | } | |
846 | } | |
847 | ||
848 | ||
849 | /* Generate code to perform the integral promotions (ANSI 6.2.1.1) on | |
850 | the value on the top of the stack, as described by VALUE. Assume | |
851 | the value has integral type. */ | |
852 | static void | |
fba45db2 | 853 | gen_integral_promotions (struct agent_expr *ax, struct axs_value *value) |
c906108c | 854 | { |
c5aa993b | 855 | if (!type_wider_than (value->type, builtin_type_int)) |
c906108c SS |
856 | { |
857 | gen_conversion (ax, value->type, builtin_type_int); | |
858 | value->type = builtin_type_int; | |
859 | } | |
c5aa993b | 860 | else if (!type_wider_than (value->type, builtin_type_unsigned_int)) |
c906108c SS |
861 | { |
862 | gen_conversion (ax, value->type, builtin_type_unsigned_int); | |
863 | value->type = builtin_type_unsigned_int; | |
864 | } | |
865 | } | |
866 | ||
867 | ||
868 | /* Generate code for a cast to TYPE. */ | |
869 | static void | |
fba45db2 | 870 | gen_cast (struct agent_expr *ax, struct axs_value *value, struct type *type) |
c906108c SS |
871 | { |
872 | /* GCC does allow casts to yield lvalues, so this should be fixed | |
873 | before merging these changes into the trunk. */ | |
874 | require_rvalue (ax, value); | |
875 | /* Dereference typedefs. */ | |
876 | type = check_typedef (type); | |
877 | ||
0004e5a2 | 878 | switch (TYPE_CODE (type)) |
c906108c SS |
879 | { |
880 | case TYPE_CODE_PTR: | |
881 | /* It's implementation-defined, and I'll bet this is what GCC | |
882 | does. */ | |
883 | break; | |
884 | ||
885 | case TYPE_CODE_ARRAY: | |
886 | case TYPE_CODE_STRUCT: | |
887 | case TYPE_CODE_UNION: | |
888 | case TYPE_CODE_FUNC: | |
889 | error ("Illegal type cast: intended type must be scalar."); | |
890 | ||
891 | case TYPE_CODE_ENUM: | |
892 | /* We don't have to worry about the size of the value, because | |
893 | all our integral values are fully sign-extended, and when | |
894 | casting pointers we can do anything we like. Is there any | |
895 | way for us to actually know what GCC actually does with a | |
896 | cast like this? */ | |
897 | value->type = type; | |
898 | break; | |
c5aa993b | 899 | |
c906108c SS |
900 | case TYPE_CODE_INT: |
901 | gen_conversion (ax, value->type, type); | |
902 | break; | |
903 | ||
904 | case TYPE_CODE_VOID: | |
905 | /* We could pop the value, and rely on everyone else to check | |
c5aa993b JM |
906 | the type and notice that this value doesn't occupy a stack |
907 | slot. But for now, leave the value on the stack, and | |
908 | preserve the "value == stack element" assumption. */ | |
c906108c SS |
909 | break; |
910 | ||
911 | default: | |
912 | error ("Casts to requested type are not yet implemented."); | |
913 | } | |
914 | ||
915 | value->type = type; | |
916 | } | |
c5aa993b | 917 | \f |
c906108c SS |
918 | |
919 | ||
c906108c SS |
920 | /* Generating bytecode from GDB expressions: arithmetic */ |
921 | ||
922 | /* Scale the integer on the top of the stack by the size of the target | |
923 | of the pointer type TYPE. */ | |
924 | static void | |
fba45db2 | 925 | gen_scale (struct agent_expr *ax, enum agent_op op, struct type *type) |
c906108c SS |
926 | { |
927 | struct type *element = TYPE_TARGET_TYPE (type); | |
928 | ||
0004e5a2 | 929 | if (TYPE_LENGTH (element) != 1) |
c906108c | 930 | { |
0004e5a2 | 931 | ax_const_l (ax, TYPE_LENGTH (element)); |
c906108c SS |
932 | ax_simple (ax, op); |
933 | } | |
934 | } | |
935 | ||
936 | ||
937 | /* Generate code for an addition; non-trivial because we deal with | |
938 | pointer arithmetic. We set VALUE to describe the result value; we | |
939 | assume VALUE1 and VALUE2 describe the two operands, and that | |
940 | they've undergone the usual binary conversions. Used by both | |
941 | BINOP_ADD and BINOP_SUBSCRIPT. NAME is used in error messages. */ | |
942 | static void | |
fba45db2 KB |
943 | gen_add (struct agent_expr *ax, struct axs_value *value, |
944 | struct axs_value *value1, struct axs_value *value2, char *name) | |
c906108c SS |
945 | { |
946 | /* Is it INT+PTR? */ | |
0004e5a2 DJ |
947 | if (TYPE_CODE (value1->type) == TYPE_CODE_INT |
948 | && TYPE_CODE (value2->type) == TYPE_CODE_PTR) | |
c906108c SS |
949 | { |
950 | /* Swap the values and proceed normally. */ | |
951 | ax_simple (ax, aop_swap); | |
952 | gen_scale (ax, aop_mul, value2->type); | |
953 | ax_simple (ax, aop_add); | |
c5aa993b | 954 | gen_extend (ax, value2->type); /* Catch overflow. */ |
c906108c SS |
955 | value->type = value2->type; |
956 | } | |
957 | ||
958 | /* Is it PTR+INT? */ | |
0004e5a2 DJ |
959 | else if (TYPE_CODE (value1->type) == TYPE_CODE_PTR |
960 | && TYPE_CODE (value2->type) == TYPE_CODE_INT) | |
c906108c SS |
961 | { |
962 | gen_scale (ax, aop_mul, value1->type); | |
963 | ax_simple (ax, aop_add); | |
c5aa993b | 964 | gen_extend (ax, value1->type); /* Catch overflow. */ |
c906108c SS |
965 | value->type = value1->type; |
966 | } | |
967 | ||
968 | /* Must be number + number; the usual binary conversions will have | |
969 | brought them both to the same width. */ | |
0004e5a2 DJ |
970 | else if (TYPE_CODE (value1->type) == TYPE_CODE_INT |
971 | && TYPE_CODE (value2->type) == TYPE_CODE_INT) | |
c906108c SS |
972 | { |
973 | ax_simple (ax, aop_add); | |
c5aa993b | 974 | gen_extend (ax, value1->type); /* Catch overflow. */ |
c906108c SS |
975 | value->type = value1->type; |
976 | } | |
977 | ||
978 | else | |
979 | error ("Illegal combination of types in %s.", name); | |
980 | ||
981 | value->kind = axs_rvalue; | |
982 | } | |
983 | ||
984 | ||
985 | /* Generate code for an addition; non-trivial because we have to deal | |
986 | with pointer arithmetic. We set VALUE to describe the result | |
987 | value; we assume VALUE1 and VALUE2 describe the two operands, and | |
988 | that they've undergone the usual binary conversions. */ | |
989 | static void | |
fba45db2 KB |
990 | gen_sub (struct agent_expr *ax, struct axs_value *value, |
991 | struct axs_value *value1, struct axs_value *value2) | |
c906108c | 992 | { |
0004e5a2 | 993 | if (TYPE_CODE (value1->type) == TYPE_CODE_PTR) |
c906108c SS |
994 | { |
995 | /* Is it PTR - INT? */ | |
0004e5a2 | 996 | if (TYPE_CODE (value2->type) == TYPE_CODE_INT) |
c906108c SS |
997 | { |
998 | gen_scale (ax, aop_mul, value1->type); | |
999 | ax_simple (ax, aop_sub); | |
c5aa993b | 1000 | gen_extend (ax, value1->type); /* Catch overflow. */ |
c906108c SS |
1001 | value->type = value1->type; |
1002 | } | |
1003 | ||
1004 | /* Is it PTR - PTR? Strictly speaking, the types ought to | |
c5aa993b JM |
1005 | match, but this is what the normal GDB expression evaluator |
1006 | tests for. */ | |
0004e5a2 | 1007 | else if (TYPE_CODE (value2->type) == TYPE_CODE_PTR |
c906108c SS |
1008 | && (TYPE_LENGTH (TYPE_TARGET_TYPE (value1->type)) |
1009 | == TYPE_LENGTH (TYPE_TARGET_TYPE (value2->type)))) | |
1010 | { | |
1011 | ax_simple (ax, aop_sub); | |
1012 | gen_scale (ax, aop_div_unsigned, value1->type); | |
c5aa993b | 1013 | value->type = builtin_type_long; /* FIXME --- should be ptrdiff_t */ |
c906108c SS |
1014 | } |
1015 | else | |
1016 | error ("\ | |
1017 | First argument of `-' is a pointer, but second argument is neither\n\ | |
1018 | an integer nor a pointer of the same type."); | |
1019 | } | |
1020 | ||
1021 | /* Must be number + number. */ | |
0004e5a2 DJ |
1022 | else if (TYPE_CODE (value1->type) == TYPE_CODE_INT |
1023 | && TYPE_CODE (value2->type) == TYPE_CODE_INT) | |
c906108c SS |
1024 | { |
1025 | ax_simple (ax, aop_sub); | |
c5aa993b | 1026 | gen_extend (ax, value1->type); /* Catch overflow. */ |
c906108c SS |
1027 | value->type = value1->type; |
1028 | } | |
c5aa993b | 1029 | |
c906108c SS |
1030 | else |
1031 | error ("Illegal combination of types in subtraction."); | |
1032 | ||
1033 | value->kind = axs_rvalue; | |
1034 | } | |
1035 | ||
1036 | /* Generate code for a binary operator that doesn't do pointer magic. | |
1037 | We set VALUE to describe the result value; we assume VALUE1 and | |
1038 | VALUE2 describe the two operands, and that they've undergone the | |
1039 | usual binary conversions. MAY_CARRY should be non-zero iff the | |
1040 | result needs to be extended. NAME is the English name of the | |
1041 | operator, used in error messages */ | |
1042 | static void | |
fba45db2 KB |
1043 | gen_binop (struct agent_expr *ax, struct axs_value *value, |
1044 | struct axs_value *value1, struct axs_value *value2, enum agent_op op, | |
1045 | enum agent_op op_unsigned, int may_carry, char *name) | |
c906108c SS |
1046 | { |
1047 | /* We only handle INT op INT. */ | |
0004e5a2 DJ |
1048 | if ((TYPE_CODE (value1->type) != TYPE_CODE_INT) |
1049 | || (TYPE_CODE (value2->type) != TYPE_CODE_INT)) | |
c906108c | 1050 | error ("Illegal combination of types in %s.", name); |
c5aa993b | 1051 | |
c906108c SS |
1052 | ax_simple (ax, |
1053 | TYPE_UNSIGNED (value1->type) ? op_unsigned : op); | |
1054 | if (may_carry) | |
c5aa993b | 1055 | gen_extend (ax, value1->type); /* catch overflow */ |
c906108c SS |
1056 | value->type = value1->type; |
1057 | value->kind = axs_rvalue; | |
1058 | } | |
1059 | ||
1060 | ||
1061 | static void | |
fba45db2 | 1062 | gen_logical_not (struct agent_expr *ax, struct axs_value *value) |
c906108c SS |
1063 | { |
1064 | if (TYPE_CODE (value->type) != TYPE_CODE_INT | |
1065 | && TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1066 | error ("Illegal type of operand to `!'."); | |
1067 | ||
1068 | gen_usual_unary (ax, value); | |
1069 | ax_simple (ax, aop_log_not); | |
1070 | value->type = builtin_type_int; | |
1071 | } | |
1072 | ||
1073 | ||
1074 | static void | |
fba45db2 | 1075 | gen_complement (struct agent_expr *ax, struct axs_value *value) |
c906108c SS |
1076 | { |
1077 | if (TYPE_CODE (value->type) != TYPE_CODE_INT) | |
1078 | error ("Illegal type of operand to `~'."); | |
1079 | ||
1080 | gen_usual_unary (ax, value); | |
1081 | gen_integral_promotions (ax, value); | |
1082 | ax_simple (ax, aop_bit_not); | |
1083 | gen_extend (ax, value->type); | |
1084 | } | |
c5aa993b | 1085 | \f |
c906108c SS |
1086 | |
1087 | ||
c906108c SS |
1088 | /* Generating bytecode from GDB expressions: * & . -> @ sizeof */ |
1089 | ||
1090 | /* Dereference the value on the top of the stack. */ | |
1091 | static void | |
fba45db2 | 1092 | gen_deref (struct agent_expr *ax, struct axs_value *value) |
c906108c SS |
1093 | { |
1094 | /* The caller should check the type, because several operators use | |
1095 | this, and we don't know what error message to generate. */ | |
0004e5a2 | 1096 | if (TYPE_CODE (value->type) != TYPE_CODE_PTR) |
8e65ff28 AC |
1097 | internal_error (__FILE__, __LINE__, |
1098 | "gen_deref: expected a pointer"); | |
c906108c SS |
1099 | |
1100 | /* We've got an rvalue now, which is a pointer. We want to yield an | |
1101 | lvalue, whose address is exactly that pointer. So we don't | |
1102 | actually emit any code; we just change the type from "Pointer to | |
1103 | T" to "T", and mark the value as an lvalue in memory. Leave it | |
1104 | to the consumer to actually dereference it. */ | |
1105 | value->type = check_typedef (TYPE_TARGET_TYPE (value->type)); | |
0004e5a2 | 1106 | value->kind = ((TYPE_CODE (value->type) == TYPE_CODE_FUNC) |
c906108c SS |
1107 | ? axs_rvalue : axs_lvalue_memory); |
1108 | } | |
1109 | ||
1110 | ||
1111 | /* Produce the address of the lvalue on the top of the stack. */ | |
1112 | static void | |
fba45db2 | 1113 | gen_address_of (struct agent_expr *ax, struct axs_value *value) |
c906108c SS |
1114 | { |
1115 | /* Special case for taking the address of a function. The ANSI | |
1116 | standard describes this as a special case, too, so this | |
1117 | arrangement is not without motivation. */ | |
0004e5a2 | 1118 | if (TYPE_CODE (value->type) == TYPE_CODE_FUNC) |
c906108c SS |
1119 | /* The value's already an rvalue on the stack, so we just need to |
1120 | change the type. */ | |
1121 | value->type = lookup_pointer_type (value->type); | |
1122 | else | |
1123 | switch (value->kind) | |
1124 | { | |
1125 | case axs_rvalue: | |
1126 | error ("Operand of `&' is an rvalue, which has no address."); | |
1127 | ||
1128 | case axs_lvalue_register: | |
1129 | error ("Operand of `&' is in a register, and has no address."); | |
1130 | ||
1131 | case axs_lvalue_memory: | |
1132 | value->kind = axs_rvalue; | |
1133 | value->type = lookup_pointer_type (value->type); | |
1134 | break; | |
1135 | } | |
1136 | } | |
1137 | ||
1138 | ||
1139 | /* A lot of this stuff will have to change to support C++. But we're | |
1140 | not going to deal with that at the moment. */ | |
1141 | ||
1142 | /* Find the field in the structure type TYPE named NAME, and return | |
1143 | its index in TYPE's field array. */ | |
1144 | static int | |
fba45db2 | 1145 | find_field (struct type *type, char *name) |
c906108c SS |
1146 | { |
1147 | int i; | |
1148 | ||
1149 | CHECK_TYPEDEF (type); | |
1150 | ||
1151 | /* Make sure this isn't C++. */ | |
1152 | if (TYPE_N_BASECLASSES (type) != 0) | |
8e65ff28 AC |
1153 | internal_error (__FILE__, __LINE__, |
1154 | "find_field: derived classes supported"); | |
c906108c SS |
1155 | |
1156 | for (i = 0; i < TYPE_NFIELDS (type); i++) | |
1157 | { | |
1158 | char *this_name = TYPE_FIELD_NAME (type, i); | |
1159 | ||
1160 | if (this_name && STREQ (name, this_name)) | |
1161 | return i; | |
1162 | ||
1163 | if (this_name[0] == '\0') | |
8e65ff28 AC |
1164 | internal_error (__FILE__, __LINE__, |
1165 | "find_field: anonymous unions not supported"); | |
c906108c SS |
1166 | } |
1167 | ||
1168 | error ("Couldn't find member named `%s' in struct/union `%s'", | |
7495dfdb | 1169 | name, TYPE_TAG_NAME (type)); |
c906108c SS |
1170 | |
1171 | return 0; | |
1172 | } | |
1173 | ||
1174 | ||
1175 | /* Generate code to push the value of a bitfield of a structure whose | |
1176 | address is on the top of the stack. START and END give the | |
1177 | starting and one-past-ending *bit* numbers of the field within the | |
1178 | structure. */ | |
1179 | static void | |
fba45db2 KB |
1180 | gen_bitfield_ref (struct agent_expr *ax, struct axs_value *value, |
1181 | struct type *type, int start, int end) | |
c906108c SS |
1182 | { |
1183 | /* Note that ops[i] fetches 8 << i bits. */ | |
1184 | static enum agent_op ops[] | |
c5aa993b JM |
1185 | = |
1186 | {aop_ref8, aop_ref16, aop_ref32, aop_ref64}; | |
c906108c SS |
1187 | static int num_ops = (sizeof (ops) / sizeof (ops[0])); |
1188 | ||
1189 | /* We don't want to touch any byte that the bitfield doesn't | |
1190 | actually occupy; we shouldn't make any accesses we're not | |
1191 | explicitly permitted to. We rely here on the fact that the | |
1192 | bytecode `ref' operators work on unaligned addresses. | |
1193 | ||
1194 | It takes some fancy footwork to get the stack to work the way | |
1195 | we'd like. Say we're retrieving a bitfield that requires three | |
1196 | fetches. Initially, the stack just contains the address: | |
c5aa993b | 1197 | addr |
c906108c | 1198 | For the first fetch, we duplicate the address |
c5aa993b | 1199 | addr addr |
c906108c SS |
1200 | then add the byte offset, do the fetch, and shift and mask as |
1201 | needed, yielding a fragment of the value, properly aligned for | |
1202 | the final bitwise or: | |
c5aa993b | 1203 | addr frag1 |
c906108c | 1204 | then we swap, and repeat the process: |
c5aa993b JM |
1205 | frag1 addr --- address on top |
1206 | frag1 addr addr --- duplicate it | |
1207 | frag1 addr frag2 --- get second fragment | |
1208 | frag1 frag2 addr --- swap again | |
1209 | frag1 frag2 frag3 --- get third fragment | |
c906108c SS |
1210 | Notice that, since the third fragment is the last one, we don't |
1211 | bother duplicating the address this time. Now we have all the | |
1212 | fragments on the stack, and we can simply `or' them together, | |
1213 | yielding the final value of the bitfield. */ | |
1214 | ||
1215 | /* The first and one-after-last bits in the field, but rounded down | |
1216 | and up to byte boundaries. */ | |
1217 | int bound_start = (start / TARGET_CHAR_BIT) * TARGET_CHAR_BIT; | |
c5aa993b JM |
1218 | int bound_end = (((end + TARGET_CHAR_BIT - 1) |
1219 | / TARGET_CHAR_BIT) | |
1220 | * TARGET_CHAR_BIT); | |
c906108c SS |
1221 | |
1222 | /* current bit offset within the structure */ | |
1223 | int offset; | |
1224 | ||
1225 | /* The index in ops of the opcode we're considering. */ | |
1226 | int op; | |
1227 | ||
1228 | /* The number of fragments we generated in the process. Probably | |
1229 | equal to the number of `one' bits in bytesize, but who cares? */ | |
1230 | int fragment_count; | |
1231 | ||
1232 | /* Dereference any typedefs. */ | |
1233 | type = check_typedef (type); | |
1234 | ||
1235 | /* Can we fetch the number of bits requested at all? */ | |
1236 | if ((end - start) > ((1 << num_ops) * 8)) | |
8e65ff28 AC |
1237 | internal_error (__FILE__, __LINE__, |
1238 | "gen_bitfield_ref: bitfield too wide"); | |
c906108c SS |
1239 | |
1240 | /* Note that we know here that we only need to try each opcode once. | |
1241 | That may not be true on machines with weird byte sizes. */ | |
1242 | offset = bound_start; | |
1243 | fragment_count = 0; | |
1244 | for (op = num_ops - 1; op >= 0; op--) | |
1245 | { | |
1246 | /* number of bits that ops[op] would fetch */ | |
1247 | int op_size = 8 << op; | |
1248 | ||
1249 | /* The stack at this point, from bottom to top, contains zero or | |
c5aa993b JM |
1250 | more fragments, then the address. */ |
1251 | ||
c906108c SS |
1252 | /* Does this fetch fit within the bitfield? */ |
1253 | if (offset + op_size <= bound_end) | |
1254 | { | |
1255 | /* Is this the last fragment? */ | |
1256 | int last_frag = (offset + op_size == bound_end); | |
1257 | ||
c5aa993b JM |
1258 | if (!last_frag) |
1259 | ax_simple (ax, aop_dup); /* keep a copy of the address */ | |
1260 | ||
c906108c SS |
1261 | /* Add the offset. */ |
1262 | gen_offset (ax, offset / TARGET_CHAR_BIT); | |
1263 | ||
1264 | if (trace_kludge) | |
1265 | { | |
1266 | /* Record the area of memory we're about to fetch. */ | |
1267 | ax_trace_quick (ax, op_size / TARGET_CHAR_BIT); | |
1268 | } | |
1269 | ||
1270 | /* Perform the fetch. */ | |
1271 | ax_simple (ax, ops[op]); | |
c5aa993b JM |
1272 | |
1273 | /* Shift the bits we have to their proper position. | |
c906108c SS |
1274 | gen_left_shift will generate right shifts when the operand |
1275 | is negative. | |
1276 | ||
c5aa993b JM |
1277 | A big-endian field diagram to ponder: |
1278 | byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7 | |
1279 | +------++------++------++------++------++------++------++------+ | |
1280 | xxxxAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBCCCCCxxxxxxxxxxx | |
1281 | ^ ^ ^ ^ | |
1282 | bit number 16 32 48 53 | |
c906108c SS |
1283 | These are bit numbers as supplied by GDB. Note that the |
1284 | bit numbers run from right to left once you've fetched the | |
1285 | value! | |
1286 | ||
c5aa993b JM |
1287 | A little-endian field diagram to ponder: |
1288 | byte 7 byte 6 byte 5 byte 4 byte 3 byte 2 byte 1 byte 0 | |
1289 | +------++------++------++------++------++------++------++------+ | |
1290 | xxxxxxxxxxxAAAAABBBBBBBBBBBBBBBBCCCCCCCCCCCCCCCCCCCCCCCCCCCCxxxx | |
1291 | ^ ^ ^ ^ ^ | |
1292 | bit number 48 32 16 4 0 | |
1293 | ||
1294 | In both cases, the most significant end is on the left | |
1295 | (i.e. normal numeric writing order), which means that you | |
1296 | don't go crazy thinking about `left' and `right' shifts. | |
1297 | ||
1298 | We don't have to worry about masking yet: | |
1299 | - If they contain garbage off the least significant end, then we | |
1300 | must be looking at the low end of the field, and the right | |
1301 | shift will wipe them out. | |
1302 | - If they contain garbage off the most significant end, then we | |
1303 | must be looking at the most significant end of the word, and | |
1304 | the sign/zero extension will wipe them out. | |
1305 | - If we're in the interior of the word, then there is no garbage | |
1306 | on either end, because the ref operators zero-extend. */ | |
d7449b42 | 1307 | if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG) |
c906108c | 1308 | gen_left_shift (ax, end - (offset + op_size)); |
c5aa993b | 1309 | else |
c906108c SS |
1310 | gen_left_shift (ax, offset - start); |
1311 | ||
c5aa993b | 1312 | if (!last_frag) |
c906108c SS |
1313 | /* Bring the copy of the address up to the top. */ |
1314 | ax_simple (ax, aop_swap); | |
1315 | ||
1316 | offset += op_size; | |
1317 | fragment_count++; | |
1318 | } | |
1319 | } | |
1320 | ||
1321 | /* Generate enough bitwise `or' operations to combine all the | |
1322 | fragments we left on the stack. */ | |
1323 | while (fragment_count-- > 1) | |
1324 | ax_simple (ax, aop_bit_or); | |
1325 | ||
1326 | /* Sign- or zero-extend the value as appropriate. */ | |
1327 | ((TYPE_UNSIGNED (type) ? ax_zero_ext : ax_ext) (ax, end - start)); | |
1328 | ||
1329 | /* This is *not* an lvalue. Ugh. */ | |
1330 | value->kind = axs_rvalue; | |
1331 | value->type = type; | |
1332 | } | |
1333 | ||
1334 | ||
1335 | /* Generate code to reference the member named FIELD of a structure or | |
1336 | union. The top of the stack, as described by VALUE, should have | |
1337 | type (pointer to a)* struct/union. OPERATOR_NAME is the name of | |
1338 | the operator being compiled, and OPERAND_NAME is the kind of thing | |
1339 | it operates on; we use them in error messages. */ | |
1340 | static void | |
fba45db2 KB |
1341 | gen_struct_ref (struct agent_expr *ax, struct axs_value *value, char *field, |
1342 | char *operator_name, char *operand_name) | |
c906108c SS |
1343 | { |
1344 | struct type *type; | |
1345 | int i; | |
1346 | ||
1347 | /* Follow pointers until we reach a non-pointer. These aren't the C | |
1348 | semantics, but they're what the normal GDB evaluator does, so we | |
1349 | should at least be consistent. */ | |
0004e5a2 | 1350 | while (TYPE_CODE (value->type) == TYPE_CODE_PTR) |
c906108c SS |
1351 | { |
1352 | gen_usual_unary (ax, value); | |
1353 | gen_deref (ax, value); | |
1354 | } | |
e8860ec2 | 1355 | type = check_typedef (value->type); |
c906108c SS |
1356 | |
1357 | /* This must yield a structure or a union. */ | |
1358 | if (TYPE_CODE (type) != TYPE_CODE_STRUCT | |
1359 | && TYPE_CODE (type) != TYPE_CODE_UNION) | |
1360 | error ("The left operand of `%s' is not a %s.", | |
1361 | operator_name, operand_name); | |
1362 | ||
1363 | /* And it must be in memory; we don't deal with structure rvalues, | |
1364 | or structures living in registers. */ | |
1365 | if (value->kind != axs_lvalue_memory) | |
1366 | error ("Structure does not live in memory."); | |
1367 | ||
1368 | i = find_field (type, field); | |
c5aa993b | 1369 | |
c906108c SS |
1370 | /* Is this a bitfield? */ |
1371 | if (TYPE_FIELD_PACKED (type, i)) | |
1372 | gen_bitfield_ref (ax, value, TYPE_FIELD_TYPE (type, i), | |
1373 | TYPE_FIELD_BITPOS (type, i), | |
1374 | (TYPE_FIELD_BITPOS (type, i) | |
1375 | + TYPE_FIELD_BITSIZE (type, i))); | |
1376 | else | |
1377 | { | |
1378 | gen_offset (ax, TYPE_FIELD_BITPOS (type, i) / TARGET_CHAR_BIT); | |
1379 | value->kind = axs_lvalue_memory; | |
1380 | value->type = TYPE_FIELD_TYPE (type, i); | |
1381 | } | |
1382 | } | |
1383 | ||
1384 | ||
1385 | /* Generate code for GDB's magical `repeat' operator. | |
1386 | LVALUE @ INT creates an array INT elements long, and whose elements | |
1387 | have the same type as LVALUE, located in memory so that LVALUE is | |
1388 | its first element. For example, argv[0]@argc gives you the array | |
1389 | of command-line arguments. | |
1390 | ||
1391 | Unfortunately, because we have to know the types before we actually | |
1392 | have a value for the expression, we can't implement this perfectly | |
1393 | without changing the type system, having values that occupy two | |
1394 | stack slots, doing weird things with sizeof, etc. So we require | |
1395 | the right operand to be a constant expression. */ | |
1396 | static void | |
fba45db2 KB |
1397 | gen_repeat (union exp_element **pc, struct agent_expr *ax, |
1398 | struct axs_value *value) | |
c906108c SS |
1399 | { |
1400 | struct axs_value value1; | |
1401 | /* We don't want to turn this into an rvalue, so no conversions | |
1402 | here. */ | |
1403 | gen_expr (pc, ax, &value1); | |
1404 | if (value1.kind != axs_lvalue_memory) | |
1405 | error ("Left operand of `@' must be an object in memory."); | |
1406 | ||
1407 | /* Evaluate the length; it had better be a constant. */ | |
1408 | { | |
1409 | struct value *v = const_expr (pc); | |
1410 | int length; | |
1411 | ||
c5aa993b | 1412 | if (!v) |
c906108c | 1413 | error ("Right operand of `@' must be a constant, in agent expressions."); |
0004e5a2 | 1414 | if (TYPE_CODE (v->type) != TYPE_CODE_INT) |
c906108c SS |
1415 | error ("Right operand of `@' must be an integer."); |
1416 | length = value_as_long (v); | |
1417 | if (length <= 0) | |
1418 | error ("Right operand of `@' must be positive."); | |
1419 | ||
1420 | /* The top of the stack is already the address of the object, so | |
1421 | all we need to do is frob the type of the lvalue. */ | |
1422 | { | |
1423 | /* FIXME-type-allocation: need a way to free this type when we are | |
c5aa993b | 1424 | done with it. */ |
c906108c | 1425 | struct type *range |
c5aa993b | 1426 | = create_range_type (0, builtin_type_int, 0, length - 1); |
c906108c SS |
1427 | struct type *array = create_array_type (0, value1.type, range); |
1428 | ||
1429 | value->kind = axs_lvalue_memory; | |
1430 | value->type = array; | |
1431 | } | |
1432 | } | |
1433 | } | |
1434 | ||
1435 | ||
1436 | /* Emit code for the `sizeof' operator. | |
1437 | *PC should point at the start of the operand expression; we advance it | |
1438 | to the first instruction after the operand. */ | |
1439 | static void | |
fba45db2 KB |
1440 | gen_sizeof (union exp_element **pc, struct agent_expr *ax, |
1441 | struct axs_value *value) | |
c906108c SS |
1442 | { |
1443 | /* We don't care about the value of the operand expression; we only | |
1444 | care about its type. However, in the current arrangement, the | |
1445 | only way to find an expression's type is to generate code for it. | |
1446 | So we generate code for the operand, and then throw it away, | |
1447 | replacing it with code that simply pushes its size. */ | |
1448 | int start = ax->len; | |
1449 | gen_expr (pc, ax, value); | |
1450 | ||
1451 | /* Throw away the code we just generated. */ | |
1452 | ax->len = start; | |
c5aa993b | 1453 | |
c906108c SS |
1454 | ax_const_l (ax, TYPE_LENGTH (value->type)); |
1455 | value->kind = axs_rvalue; | |
1456 | value->type = builtin_type_int; | |
1457 | } | |
c906108c | 1458 | \f |
c5aa993b | 1459 | |
c906108c SS |
1460 | /* Generating bytecode from GDB expressions: general recursive thingy */ |
1461 | ||
1462 | /* A gen_expr function written by a Gen-X'er guy. | |
1463 | Append code for the subexpression of EXPR starting at *POS_P to AX. */ | |
1464 | static void | |
fba45db2 KB |
1465 | gen_expr (union exp_element **pc, struct agent_expr *ax, |
1466 | struct axs_value *value) | |
c906108c SS |
1467 | { |
1468 | /* Used to hold the descriptions of operand expressions. */ | |
1469 | struct axs_value value1, value2; | |
1470 | enum exp_opcode op = (*pc)[0].opcode; | |
1471 | ||
1472 | /* If we're looking at a constant expression, just push its value. */ | |
1473 | { | |
1474 | struct value *v = maybe_const_expr (pc); | |
c5aa993b | 1475 | |
c906108c SS |
1476 | if (v) |
1477 | { | |
1478 | ax_const_l (ax, value_as_long (v)); | |
1479 | value->kind = axs_rvalue; | |
1480 | value->type = check_typedef (VALUE_TYPE (v)); | |
1481 | return; | |
1482 | } | |
1483 | } | |
1484 | ||
1485 | /* Otherwise, go ahead and generate code for it. */ | |
1486 | switch (op) | |
1487 | { | |
1488 | /* Binary arithmetic operators. */ | |
1489 | case BINOP_ADD: | |
1490 | case BINOP_SUB: | |
1491 | case BINOP_MUL: | |
1492 | case BINOP_DIV: | |
1493 | case BINOP_REM: | |
1494 | case BINOP_SUBSCRIPT: | |
1495 | case BINOP_BITWISE_AND: | |
1496 | case BINOP_BITWISE_IOR: | |
1497 | case BINOP_BITWISE_XOR: | |
1498 | (*pc)++; | |
1499 | gen_expr (pc, ax, &value1); | |
1500 | gen_usual_unary (ax, &value1); | |
1501 | gen_expr (pc, ax, &value2); | |
1502 | gen_usual_unary (ax, &value2); | |
1503 | gen_usual_arithmetic (ax, &value1, &value2); | |
1504 | switch (op) | |
1505 | { | |
1506 | case BINOP_ADD: | |
1507 | gen_add (ax, value, &value1, &value2, "addition"); | |
1508 | break; | |
1509 | case BINOP_SUB: | |
1510 | gen_sub (ax, value, &value1, &value2); | |
1511 | break; | |
1512 | case BINOP_MUL: | |
1513 | gen_binop (ax, value, &value1, &value2, | |
1514 | aop_mul, aop_mul, 1, "multiplication"); | |
1515 | break; | |
1516 | case BINOP_DIV: | |
1517 | gen_binop (ax, value, &value1, &value2, | |
1518 | aop_div_signed, aop_div_unsigned, 1, "division"); | |
1519 | break; | |
1520 | case BINOP_REM: | |
1521 | gen_binop (ax, value, &value1, &value2, | |
1522 | aop_rem_signed, aop_rem_unsigned, 1, "remainder"); | |
1523 | break; | |
1524 | case BINOP_SUBSCRIPT: | |
1525 | gen_add (ax, value, &value1, &value2, "array subscripting"); | |
1526 | if (TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1527 | error ("Illegal combination of types in array subscripting."); | |
1528 | gen_deref (ax, value); | |
1529 | break; | |
1530 | case BINOP_BITWISE_AND: | |
1531 | gen_binop (ax, value, &value1, &value2, | |
1532 | aop_bit_and, aop_bit_and, 0, "bitwise and"); | |
1533 | break; | |
1534 | ||
1535 | case BINOP_BITWISE_IOR: | |
1536 | gen_binop (ax, value, &value1, &value2, | |
1537 | aop_bit_or, aop_bit_or, 0, "bitwise or"); | |
1538 | break; | |
1539 | ||
1540 | case BINOP_BITWISE_XOR: | |
1541 | gen_binop (ax, value, &value1, &value2, | |
1542 | aop_bit_xor, aop_bit_xor, 0, "bitwise exclusive-or"); | |
1543 | break; | |
1544 | ||
1545 | default: | |
1546 | /* We should only list operators in the outer case statement | |
c5aa993b | 1547 | that we actually handle in the inner case statement. */ |
8e65ff28 AC |
1548 | internal_error (__FILE__, __LINE__, |
1549 | "gen_expr: op case sets don't match"); | |
c906108c SS |
1550 | } |
1551 | break; | |
1552 | ||
1553 | /* Note that we need to be a little subtle about generating code | |
c5aa993b JM |
1554 | for comma. In C, we can do some optimizations here because |
1555 | we know the left operand is only being evaluated for effect. | |
1556 | However, if the tracing kludge is in effect, then we always | |
1557 | need to evaluate the left hand side fully, so that all the | |
1558 | variables it mentions get traced. */ | |
c906108c SS |
1559 | case BINOP_COMMA: |
1560 | (*pc)++; | |
1561 | gen_expr (pc, ax, &value1); | |
1562 | /* Don't just dispose of the left operand. We might be tracing, | |
c5aa993b JM |
1563 | in which case we want to emit code to trace it if it's an |
1564 | lvalue. */ | |
c906108c SS |
1565 | gen_traced_pop (ax, &value1); |
1566 | gen_expr (pc, ax, value); | |
1567 | /* It's the consumer's responsibility to trace the right operand. */ | |
1568 | break; | |
c5aa993b | 1569 | |
c906108c SS |
1570 | case OP_LONG: /* some integer constant */ |
1571 | { | |
1572 | struct type *type = (*pc)[1].type; | |
1573 | LONGEST k = (*pc)[2].longconst; | |
1574 | (*pc) += 4; | |
1575 | gen_int_literal (ax, value, k, type); | |
1576 | } | |
c5aa993b | 1577 | break; |
c906108c SS |
1578 | |
1579 | case OP_VAR_VALUE: | |
1580 | gen_var_ref (ax, value, (*pc)[2].symbol); | |
1581 | (*pc) += 4; | |
1582 | break; | |
1583 | ||
1584 | case OP_REGISTER: | |
1585 | { | |
1586 | int reg = (int) (*pc)[1].longconst; | |
1587 | (*pc) += 3; | |
1588 | value->kind = axs_lvalue_register; | |
1589 | value->u.reg = reg; | |
1590 | value->type = REGISTER_VIRTUAL_TYPE (reg); | |
1591 | } | |
c5aa993b | 1592 | break; |
c906108c SS |
1593 | |
1594 | case OP_INTERNALVAR: | |
1595 | error ("GDB agent expressions cannot use convenience variables."); | |
1596 | ||
c5aa993b | 1597 | /* Weirdo operator: see comments for gen_repeat for details. */ |
c906108c SS |
1598 | case BINOP_REPEAT: |
1599 | /* Note that gen_repeat handles its own argument evaluation. */ | |
1600 | (*pc)++; | |
1601 | gen_repeat (pc, ax, value); | |
1602 | break; | |
1603 | ||
1604 | case UNOP_CAST: | |
1605 | { | |
1606 | struct type *type = (*pc)[1].type; | |
1607 | (*pc) += 3; | |
1608 | gen_expr (pc, ax, value); | |
1609 | gen_cast (ax, value, type); | |
1610 | } | |
c5aa993b | 1611 | break; |
c906108c SS |
1612 | |
1613 | case UNOP_MEMVAL: | |
1614 | { | |
1615 | struct type *type = check_typedef ((*pc)[1].type); | |
1616 | (*pc) += 3; | |
1617 | gen_expr (pc, ax, value); | |
1618 | /* I'm not sure I understand UNOP_MEMVAL entirely. I think | |
1619 | it's just a hack for dealing with minsyms; you take some | |
1620 | integer constant, pretend it's the address of an lvalue of | |
1621 | the given type, and dereference it. */ | |
1622 | if (value->kind != axs_rvalue) | |
1623 | /* This would be weird. */ | |
8e65ff28 AC |
1624 | internal_error (__FILE__, __LINE__, |
1625 | "gen_expr: OP_MEMVAL operand isn't an rvalue???"); | |
c906108c SS |
1626 | value->type = type; |
1627 | value->kind = axs_lvalue_memory; | |
1628 | } | |
c5aa993b | 1629 | break; |
c906108c SS |
1630 | |
1631 | case UNOP_NEG: | |
1632 | (*pc)++; | |
1633 | /* -FOO is equivalent to 0 - FOO. */ | |
1634 | gen_int_literal (ax, &value1, (LONGEST) 0, builtin_type_int); | |
c5aa993b | 1635 | gen_usual_unary (ax, &value1); /* shouldn't do much */ |
c906108c SS |
1636 | gen_expr (pc, ax, &value2); |
1637 | gen_usual_unary (ax, &value2); | |
1638 | gen_usual_arithmetic (ax, &value1, &value2); | |
1639 | gen_sub (ax, value, &value1, &value2); | |
1640 | break; | |
1641 | ||
1642 | case UNOP_LOGICAL_NOT: | |
1643 | (*pc)++; | |
1644 | gen_expr (pc, ax, value); | |
1645 | gen_logical_not (ax, value); | |
1646 | break; | |
1647 | ||
1648 | case UNOP_COMPLEMENT: | |
1649 | (*pc)++; | |
1650 | gen_expr (pc, ax, value); | |
1651 | gen_complement (ax, value); | |
1652 | break; | |
1653 | ||
1654 | case UNOP_IND: | |
1655 | (*pc)++; | |
1656 | gen_expr (pc, ax, value); | |
1657 | gen_usual_unary (ax, value); | |
1658 | if (TYPE_CODE (value->type) != TYPE_CODE_PTR) | |
1659 | error ("Argument of unary `*' is not a pointer."); | |
1660 | gen_deref (ax, value); | |
1661 | break; | |
1662 | ||
1663 | case UNOP_ADDR: | |
1664 | (*pc)++; | |
1665 | gen_expr (pc, ax, value); | |
1666 | gen_address_of (ax, value); | |
1667 | break; | |
1668 | ||
1669 | case UNOP_SIZEOF: | |
1670 | (*pc)++; | |
1671 | /* Notice that gen_sizeof handles its own operand, unlike most | |
c5aa993b JM |
1672 | of the other unary operator functions. This is because we |
1673 | have to throw away the code we generate. */ | |
c906108c SS |
1674 | gen_sizeof (pc, ax, value); |
1675 | break; | |
1676 | ||
1677 | case STRUCTOP_STRUCT: | |
1678 | case STRUCTOP_PTR: | |
1679 | { | |
1680 | int length = (*pc)[1].longconst; | |
1681 | char *name = &(*pc)[2].string; | |
1682 | ||
1683 | (*pc) += 4 + BYTES_TO_EXP_ELEM (length + 1); | |
1684 | gen_expr (pc, ax, value); | |
1685 | if (op == STRUCTOP_STRUCT) | |
1686 | gen_struct_ref (ax, value, name, ".", "structure or union"); | |
1687 | else if (op == STRUCTOP_PTR) | |
1688 | gen_struct_ref (ax, value, name, "->", | |
1689 | "pointer to a structure or union"); | |
1690 | else | |
1691 | /* If this `if' chain doesn't handle it, then the case list | |
c5aa993b | 1692 | shouldn't mention it, and we shouldn't be here. */ |
8e65ff28 AC |
1693 | internal_error (__FILE__, __LINE__, |
1694 | "gen_expr: unhandled struct case"); | |
c906108c | 1695 | } |
c5aa993b | 1696 | break; |
c906108c SS |
1697 | |
1698 | case OP_TYPE: | |
1699 | error ("Attempt to use a type name as an expression."); | |
1700 | ||
1701 | default: | |
1702 | error ("Unsupported operator in expression."); | |
1703 | } | |
1704 | } | |
c906108c | 1705 | \f |
c5aa993b JM |
1706 | |
1707 | ||
c906108c SS |
1708 | /* Generating bytecode from GDB expressions: driver */ |
1709 | ||
1710 | /* Given a GDB expression EXPR, produce a string of agent bytecode | |
1711 | which computes its value. Return the agent expression, and set | |
1712 | *VALUE to describe its type, and whether it's an lvalue or rvalue. */ | |
1713 | struct agent_expr * | |
fba45db2 | 1714 | expr_to_agent (struct expression *expr, struct axs_value *value) |
c906108c SS |
1715 | { |
1716 | struct cleanup *old_chain = 0; | |
6426a772 | 1717 | struct agent_expr *ax = new_agent_expr (0); |
c906108c SS |
1718 | union exp_element *pc; |
1719 | ||
f23d52e0 | 1720 | old_chain = make_cleanup_free_agent_expr (ax); |
c906108c SS |
1721 | |
1722 | pc = expr->elts; | |
1723 | trace_kludge = 0; | |
1724 | gen_expr (&pc, ax, value); | |
1725 | ||
1726 | /* We have successfully built the agent expr, so cancel the cleanup | |
1727 | request. If we add more cleanups that we always want done, this | |
1728 | will have to get more complicated. */ | |
1729 | discard_cleanups (old_chain); | |
1730 | return ax; | |
1731 | } | |
1732 | ||
1733 | ||
6426a772 | 1734 | #if 0 /* not used */ |
c906108c SS |
1735 | /* Given a GDB expression EXPR denoting an lvalue in memory, produce a |
1736 | string of agent bytecode which will leave its address and size on | |
1737 | the top of stack. Return the agent expression. | |
1738 | ||
1739 | Not sure this function is useful at all. */ | |
1740 | struct agent_expr * | |
fba45db2 | 1741 | expr_to_address_and_size (struct expression *expr) |
c906108c SS |
1742 | { |
1743 | struct axs_value value; | |
1744 | struct agent_expr *ax = expr_to_agent (expr, &value); | |
1745 | ||
1746 | /* Complain if the result is not a memory lvalue. */ | |
1747 | if (value.kind != axs_lvalue_memory) | |
1748 | { | |
1749 | free_agent_expr (ax); | |
1750 | error ("Expression does not denote an object in memory."); | |
1751 | } | |
1752 | ||
1753 | /* Push the object's size on the stack. */ | |
1754 | ax_const_l (ax, TYPE_LENGTH (value.type)); | |
1755 | ||
1756 | return ax; | |
1757 | } | |
6426a772 | 1758 | #endif |
c906108c SS |
1759 | |
1760 | /* Given a GDB expression EXPR, return bytecode to trace its value. | |
1761 | The result will use the `trace' and `trace_quick' bytecodes to | |
1762 | record the value of all memory touched by the expression. The | |
1763 | caller can then use the ax_reqs function to discover which | |
1764 | registers it relies upon. */ | |
1765 | struct agent_expr * | |
fba45db2 | 1766 | gen_trace_for_expr (CORE_ADDR scope, struct expression *expr) |
c906108c SS |
1767 | { |
1768 | struct cleanup *old_chain = 0; | |
1769 | struct agent_expr *ax = new_agent_expr (scope); | |
1770 | union exp_element *pc; | |
1771 | struct axs_value value; | |
1772 | ||
f23d52e0 | 1773 | old_chain = make_cleanup_free_agent_expr (ax); |
c906108c SS |
1774 | |
1775 | pc = expr->elts; | |
1776 | trace_kludge = 1; | |
1777 | gen_expr (&pc, ax, &value); | |
1778 | ||
1779 | /* Make sure we record the final object, and get rid of it. */ | |
1780 | gen_traced_pop (ax, &value); | |
1781 | ||
1782 | /* Oh, and terminate. */ | |
1783 | ax_simple (ax, aop_end); | |
1784 | ||
1785 | /* We have successfully built the agent expr, so cancel the cleanup | |
1786 | request. If we add more cleanups that we always want done, this | |
1787 | will have to get more complicated. */ | |
1788 | discard_cleanups (old_chain); | |
1789 | return ax; | |
1790 | } | |
c5aa993b | 1791 | \f |
c906108c SS |
1792 | |
1793 | ||
c906108c SS |
1794 | /* The "agent" command, for testing: compile and disassemble an expression. */ |
1795 | ||
1796 | static void | |
fba45db2 | 1797 | print_axs_value (struct ui_file *f, struct axs_value *value) |
c906108c SS |
1798 | { |
1799 | switch (value->kind) | |
1800 | { | |
1801 | case axs_rvalue: | |
1802 | fputs_filtered ("rvalue", f); | |
1803 | break; | |
1804 | ||
1805 | case axs_lvalue_memory: | |
1806 | fputs_filtered ("memory lvalue", f); | |
1807 | break; | |
1808 | ||
1809 | case axs_lvalue_register: | |
1810 | fprintf_filtered (f, "register %d lvalue", value->u.reg); | |
1811 | break; | |
1812 | } | |
1813 | ||
1814 | fputs_filtered (" : ", f); | |
1815 | type_print (value->type, "", f, -1); | |
1816 | } | |
1817 | ||
1818 | ||
1819 | static void | |
fba45db2 | 1820 | agent_command (char *exp, int from_tty) |
c906108c SS |
1821 | { |
1822 | struct cleanup *old_chain = 0; | |
1823 | struct expression *expr; | |
1824 | struct agent_expr *agent; | |
6426a772 | 1825 | struct frame_info *fi = get_current_frame (); /* need current scope */ |
c906108c SS |
1826 | |
1827 | /* We don't deal with overlay debugging at the moment. We need to | |
1828 | think more carefully about this. If you copy this code into | |
1829 | another command, change the error message; the user shouldn't | |
1830 | have to know anything about agent expressions. */ | |
1831 | if (overlay_debugging) | |
1832 | error ("GDB can't do agent expression translation with overlays."); | |
1833 | ||
1834 | if (exp == 0) | |
1835 | error_no_arg ("expression to translate"); | |
c5aa993b | 1836 | |
c906108c | 1837 | expr = parse_expression (exp); |
c13c43fd | 1838 | old_chain = make_cleanup (free_current_contents, &expr); |
c906108c | 1839 | agent = gen_trace_for_expr (fi->pc, expr); |
f23d52e0 | 1840 | make_cleanup_free_agent_expr (agent); |
c906108c | 1841 | ax_print (gdb_stdout, agent); |
085dd6e6 JM |
1842 | |
1843 | /* It would be nice to call ax_reqs here to gather some general info | |
1844 | about the expression, and then print out the result. */ | |
c906108c SS |
1845 | |
1846 | do_cleanups (old_chain); | |
1847 | dont_repeat (); | |
1848 | } | |
c906108c | 1849 | \f |
c5aa993b | 1850 | |
c906108c SS |
1851 | /* Initialization code. */ |
1852 | ||
a14ed312 | 1853 | void _initialize_ax_gdb (void); |
c906108c | 1854 | void |
fba45db2 | 1855 | _initialize_ax_gdb (void) |
c906108c | 1856 | { |
c906108c SS |
1857 | add_cmd ("agent", class_maintenance, agent_command, |
1858 | "Translate an expression into remote agent bytecode.", | |
1859 | &maintenancelist); | |
1860 | } |